-LRB- CNN -RRB- -- Toronto police made a gruesome discovery Wednesday when they opened a suitcase that two boaters on Lake Ontario had towed back to shore .

Inside was a badly decomposed human torso , its gender unknown .

Investigators are in touch with two other police departments investigating the recent discovery of body parts in their jurisdictions , said Toronto Det. Leslie Dunkley .

`` It is a very serious case and a very serious incident and we are going to do our best to get to the bottom of it , '' Dunkley told reporters Wednesday afternoon .

The floating suitcase was spotted 1.5 miles offshore and was brought to Bluffer 's Park , police said . A post-mortem examination is scheduled for Thursday .

Authorities have been investigating the death of Guang Hua Liu , whose body parts were found in mid-August in several places . The investigation began along the Credit River in Mississauga , west of Toronto .

Liu 's torso is still missing .

CNN affiliate CTV said Liu , 41 , was a Canadian citizen of Chinese descent who once owned a spa in Toronto . She lived in Scarborough and was the single mother of three .

Peel Regional Police , near Toronto , last week said an arrest was made in Liu 's death .

Wednesday 's discovery of the suitcase came one week after a woman 's torso was found in the Canadian portion of the Niagara River .

Niagara Regional Police said the unidentified white woman , likely in her mid-20s to early 40s , was a homicide victim . The torso was recovered near the Rainbow Bridge close to Niagara Falls .

The Niagara River case is not related to Liu 's death , police have said .

The Niagara River connects Lake Erie and Lake Ontario .

Police try to ID dismembered body found in Niagara River

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Police in touch with other departments

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Torso of Toronto-area woman is missing

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Boaters on Lake Ontario in Canada bring a suitcase to shore

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The suitcase contains human remains , police say